Rapid generation advanced for breeding of sorghum lines tolerant to low phosphorous condition

Sorghum lines tolerant to low phosphorous soil condition is essential to sorghum production in acid soil of Indonesia. An indirect breeding program to develop sorghum lines tolerant to low phosphorous soil condition had been conducted at the IPB University with Single Seed Decent method, which allow for generation advanced without selection. The population was developed from a cross of B69 x Numbu that have difference in tolerance to low P soil condition. The F2 generation was started in 2012 and advanced to 201 F6 recombinant inbred lines in 2016. The F6 lines were selected for good agronomic characters and followed by selection under low P and optimum P soil conditions in 2017. The single seed decent method was able to maintain wide genetic variability in the advanced generation for plant height, number of leaves, panicle length, panicle weight, and seed yield/plant. Selection based on Low P sensitivity index resulted in 12 sorghum lines selected as tolerant to low P soil conditions. This study showed that indirect breeding through rapid generation advances without selection can be used to develop sorghum lines with adaptation to unfavorable environment conditions.